Carburetor



Sept. 19, 1933. G. A. WAHLMARK CARBURETOR Original Filed Nov. 16, 1929 Patented Sept. 19, 1933 'CARBURETOR Gunnar A. Wahlmark,

ricchioni, Ill., assigner of one-third to Ernest J. Svenson and Charles H. Rystrom, Rockford, Ill.

Application November 16,

1929, Serial No.

407,596. rRenewed January 7, 1933 13 Claims.

The invention relates generally tocarburetors and more particularly to carburetor-s adapted for use with internal combustion engines.

The primary object of the present invention is to provide a new and improved carburetor wherein the necessity for high air velocitiesis materially reduced by providing for a downward movement of theair past the fuel `discharge member and into the intake manifold so that the moving air does not have to lift the particles of fuel and the tendency of the vaporized fuel to condense is substantially eliminated.

Another object is to provide a new and improved carburetor having the parts thereof arranged so that the main air supply may flow through the carburetor without making sharp turns which might cause variation in the operation of th carburetor at its various adjusted positions.

Another object is to provide a carburetor having a fuel discharge member with a plurality of ducts therein arranged to discharge fuel into 'the carburetor at varying heights above the normal liquid fuel level, together with means for controlling the various ,discharge ducts so that the ducts which discharge closest to the fuel level are utilized to supply fuel for the lower ranges of motor speeds, the control means being operable to bring the other fuel discharge ducts into play so as to supply additional fuel for the higherranges of speeds.

Another object is to provide a carburetor composed of a minimum number of parts each of which is simple in form; and which may be readily assembled to provide a compact and eiiicient carburetor.

Another object is to provide a carburetor havving a. new and improved fuel discharge member embodying a `fuel distributing chamber from which fuel may pass'into the main mixing chamber through a plurality of discharge ducts, the fuel dischargemember having an air passage opening in the direction from which the main air supply comes and arranged to discharge air I into the. distributing chamber to be mixed with the fuel and discharged therewith through the discharge ducts.

Other objects and advantages will become apparent from the followingrdescription taken in connection with the accompanying drawing, in which:

Figure 1 is a vertical sectional view of a carburetor embodying the preferred form of the invention, the section being taken along the line (Cl. 2in-62) Fig. 2 is a vertical sectional view of the carburetor taken along the line 2-2 of Fig. 3 showing the parts of the carburetor in idling position.

Fig. 3 is a plan section of the carburetor taken along the line 3--3 of Fig. 2 with the cover and throttle member removed.

Fig. 4 is a sectional view taken along the line 4-4 of Fig. l.

While the invention is susceptible of various modifications and alternative constructions, I have shown in the drawing and will herein describe in detail the preferred embodiment, but it is to be understood that I do not thereby intend to limit the invention to the speciflcform disclosed, but intend to cover allmodifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

In the drawing the invention is illustrated as embodied in a carburetor having a. main body of box-like form provided by a casting 9 having a bottom wall 10, upstanding outer side Walls 11 and an annular vertical inner wall 12 spaced from the side walls l1 to provide an intermediate chamber 13. The annular wall l2 also provides a vertical passageway 14 extending through the body. A narrow bar 15 extending diametrically across the lower end of the passageway 14 supports a fuel discharge member 16 within the passageway so that air drawn through the passageway may be mixed with fuel to provide a combustible fuel mixture for an internal combustion motor. At the lower end of the passageway a flange 17 (Fig. 2) is formed on the body and adapted for connection to the intake manifold (not shown) of a motor so that during operation of the motor, air will be drawn downwardly through the passageway 14 past the fuel discharge 95 member 16.

The chamber 13 surrounding the annular wall l2 serves as a fuel supplychamber and is closed at its upper end by means of a removablecover plate 18 suitably secured in position on the casting 9 and having an aperture 19 therein arranged to register with the passageway le so as to permit air to move downwardly therethrough. Liquid fuel is supplied to the chamber. 13 through a passage 19a (Fig. 1) in the casting, the passage being suitably connected to a supply tank (not shown). To maintain a constant fuel level With-l in the chamber a vfioat-eperated valve 20 isV mounted within the chamber. A sleeve 21 (Fig. f. l) positioned in the passage i9ai slidably sip- M9 itil@ ports the valve 20 in vertical position and provides a valve seat therefor.

To control the valve 20 a pair of floats 22 are positioned in two adjacent corners of the chamber 13 on the opposite sides of the chamber. Each float is connected by means of an arm 23 to a horizontal rock shaft 24 mounted in the side walls 11, thearms extending through the narrow spaces on the opposite sides cf the annular wall 12 and being secured to the rock shaft 24 adjacent the ends thereof. At substantially the mid-point of the rock shaft another arm 25 is secured with the end thereof engaging the upper end of the valve member 20 so that rocking movement of the shaft 24 serves to move the valve toward and away from the valve seat. Through the action of the float valve 20, the fuel is maintained at a constant level within the chamber 13, this level being indicated by a dotted line in Figs. 1 and 2.

Liquid fuel from within the float chamber 13 passes to the fuel discharge member 16 through a horizontal bore 26 (Fig. 1) formed in the bottom wall 10 and the radial bracket 15, the flow of fuel into the bore 26 through a port 26a being controlled by a vertically adjustable needle valve 27 mounted in the casting 9.

In order that the fuel discharged from the member 16 may be thoroughly mixed with air to form a combustible fuel mixture, means is pos!- tioned within the passageway 14 arranged to cause air passing downwardly through the passage to suck fuel out of the discharge member and to atomize it into a readily combustible mixture which passes out the lower end of passageway 14 for transmission to the motor. In the preferred form of the invention a plurality of Venturi passages are arranged with the throats of the passages positioned so that the liquid fuel will be drawn into the passages on the expansion side ofthe throats. To this end a throttle sleeve 28 is supported and guided for movement coaxially with respect to the passageway 14 by means of a trunk piston 29 slidably mounted in a cylinder 30 carried on the removable cover plate 18 of the carburetor. To permit passage of air downwardly into the passageway 14 the cylinder 30 is made of a diameter substantially smaller than the passageway 14 and is secured to the plate 18 by a plurality of comparatively thin radial webs 31 which extend from the lower edge of the cylinder to the cover-plate at circumferentially spaced points about the cylinder. Thus the air may move along a substantially straight path downwardly about the cylinder 30 and into the passageway 14 as indicated by the arrows in Figs. 1 and 2.

The invention contemplates the mixing of the air with the fuel in successive stages and to this end the throttle sleeve 28 is arranged so that it extends downwardly around the upper portion of the fuel discharge member 16 so as to define an inner annular passage 32 Figs. 1 and 4) between the fuel discharge member 16 and the sleeve 28 and to define an outer annular passage 33 be tween the sleeve 28 and a sleeve 33a mounted within the passageway 14. Air is supplied to the inner annular passage 32 through a plurality of apertures 34 formed in the sleeve 28 below the lower end of the cylinder 30 and in order that there may be a Venturi effect upon the air passing therethrough, the inner surface of the sleeve is formed so as to taperinwardly and downwardly from the apertures 34 to a point 35 which constitutes the throat of the Venturi passage. From this point the surface of the sleeve 28 tapers outwardly to the lower end of the sleeve. The outer annular passage 33 is also in the form of a venturi, this being accomplished by sloping the outer surface of the sleeve 28 outwardly and downwardly from the apertures 34 to a level indicated at 36, which constitutes the throat of the venturi, and then sloping the surface inwardly and downwardly to the lower end of the sleeve.

The various parts of the carburetor are proportioned so that vertical movement of the throttle sleeve 28 serves to vary the size of the inner and outer annular Venturi openings 32 and 33 arid to this end the inner surface of the sleeve 33 slopes inwardly from the two ends to the level 38 intermediate the upper and lower ends of the sleeve. Thus when the throttle sleeve 28 is moved downwardly from the position shown in Fig. 1 to the position shown in Fig. 2, the outer Venturi passage 33 will be gradually closed and the outer surface of the throttle sleeve below the level 36 will be moved into abutment with the outer sleeve 33 to limit the throttle movement. During such downward movement of the throttle sleeve 28 the size of the inner passage 32 is gradually reduced until, in the lowermostl position of the throttle sleeve, as shown in Fig. 2, a comparatively small annular opening is left between the fuel discharge member 16 and the sleeve 28 so as to allow passage of sufficient air to provide an idling mixture for the motor.

In order that the fuel discharge member 16 may cooperate with the throttle sleeve 28 to change the size of the inner passage 32 during movement of the throttle sleeve, the fuel discharge member is annular in horizontal cross section and is of greatest diameter at a level 39 intermediate the top and bottom of the member and tapers gradually from the level 39 toward the top and bottom of the member. Thus Aa downwardly and inwardly tapering surface 40 is 1 provided on the lower portion of the member 16 which cooperates with the outwardly and downwardly tapering inner surface of the throttle sleeve to form the expansion side of the Venturi passage 32 when the throttle sleeve 28 is in its lower or idling position (Fig. 2).

As the air moves through the inner passage 32 its velocity gradually increases as it approaches the throat 35 thereof, an`d due to the compressible nature of air, there is also a. slight compression of the air and after the air has passed the throat 35 of the venturi there is a decrease in its velocity and the air gradually expands so that there is a difference in pressure between the air on the two sides of the throat of the venturi.

The present invention utilizes this difference in pressure on the two sides of the Venturi throat to control the quantity of fuel drawn from the fuel discharge member 16 into the Venturi passage 32. To this end a plurality of fuel discharge ducts 41 are formed in the member 16 at points spaced vertically and circumferentially of the fuel discharge member, all of the ducts being arranged so that their outer ends terminate in the upwardly and inwardly tapering surface of the member 16 above the level 39. The ducts 41 are preferably formed by horizontal bores extending radially into the member 16 into communication with a plurality of longitudinal slots 42 (Fig. 4)

formed in the outer surface of a plug 43 which is 1 positioned in a vertical bore 44 formed in the discharge member. The plug 43 (as shown in Fig. 1) extends downwardly into the bore 44 to a point slightly below the normal fuel level at which point a distributing chamber 45 (Fig. 1)

is formed between the lowerend of the plug 43 and the upper end of a stemv 43 which extends upwardly into the bore 44. Thus fuel from the iloat chamber'13 maypass through the horizontal charge ducts fil may he changed. Thus hy varying the size o the distributing chamber 45 in this manner, the amount oi air or fuel which may pass through the discharge ducts {ll may be controlled.

IEhe range of movement of the throttle sleeve 23 ispreferahly such that the throat 35` thereof may be moved from its lower position as shown in Fig. 2 upwardly past all of the fuel discharge ducts 41 to the position shown-in Fig. l and thus it willbe seen that by adjustment of the throttle sleeve the number of ducts d1 which open into the expansion side of the Venturi passage 32 may he varied at The air passing through the expansion side of the venturi moves directly acrossthe ends of/ the discharge ducts d1 positioned below the throat of the venturi and this air has an aspirating effect which tends to draw fuel from the distributing chamber d5 through i tending from the upper end of the fuel discharge memoer ld downwardly through the plug 4.3 into theY distributing chamber 45. Thus through the medium of the air passage i3 the fuel in the distributing chamber t5 is subjected to the pressure from the compression sideoi' the Venturi passage 32 which tends to iorce the iuel'thrcugh the ducts il which, at the particular time, arepositioned so that their discharge ends open into the expansion side` of the venturi.

it will oe seen, however. that when any one of the ducts el has its discharge end positioned above or on the compression side of the throat 35 of the venturi 32 ,the pressure on the compression side of the venturi will act through the duct il to oilset the equal pressure' applied through the air passage 48 andfhence the duct or ducts lil in this position will not act as fuel discharge passages. These ducts may also supply air to the distributing vchaxriloer to be mixed with the liquid fuel and discharged therewith through the ducts opening below the Venturi` throat 35.

The upper end of the Vair passage 43 is flared outwardly as shown in `Fig. l, so that when the motor speed hasjbeen increased to its highest point, the rush of.' the air past the upper edge of Athe passage i8 will aspirato fuel upwardly through the passage. At such high speeds the velocity of the air moving through the annular Venturi passage 32Nis sullcient to draw fuel through `all of the ducts `t1 without the aid of pressure acting through the passage i3 so that thelutilization of the passage 48 for discharging fuel does not impair theeiciency of the carbuinner passage 32 where it is mixed with a greater quantity of air. From the inner passage 32 the fuel mixture moves into the space between the lower tapering surface 40 ofthe fuel discharge member `and the outer sleeve 38 to be mixed with the air which comes through the outer annular ,passage 33 so as to produce a .properly proportional uel mixture.

With the fuel discharge ducts 41 and the controlling throttle sleeve 28 arranged in the relation herein. shown, the ducts 41 whose discharge ends are the shortest distance above the fuel level are utilized for supplying an idling mixture sosthat less suction is required to draw the fuel` from the ducts wd the carburetor may be adjusted to provide amore satisfactory idling mix ture than has been heretofore possible.

This arrangement also insures a rapid motor acceleration since a comparatively small amount of suction is required to bring additional ducts al into play as-th'e throttle sleeve 28 is raised.

After the fuel mixture has been formed as above described, it moves downwardly out of the passageway 14 andinto the intake manifold (not shown) ofy the motor and since the moving air with which the fuel is mixed does not have to lift particles of fuel, the tendency of the fuel to condense or settle out of the air is substantially eliminated. lt will he noted that the major por- `tici-.tof the air passes through the carburetor along a substantially straight path so that the variable factors which result from the passage of air along a curved or angular path are avoided and uniform operation of the carburetor in all of its adjusted positions is assured. I

To aid in providing a rich mixture for the starting of the motor, a tubular member fir-9 is positioned about the cylinder 30 in spaced relation thereto so that the air moving downwardly into the passageway le must move through the memher a9, and a valve of the butterfly type is mounted on a shaft 5l extending across the upper end of the member ad. By closing the valve 5o the suction of the motor acts directly upon the fuel discharge ducts il so that anunusually large quantity of fuel is drawn therefrom and a rich fuel mixture is provided.

The throttle sleeve 23 is moved up and down b ymeans of a lever 52 mounted in the upper end of the cylinder 30 on a shaft 53 which extends transversely through the cylinder 3G and the tubular member 49, the outer end of the lever being connected to the piston 29 by means of alinl; 54. An arm 55 (Fig. 2) secured on the shaft 53 outside of the member ti9 may be connected to a suitable foot pedal or manual actuating device (not shown). device is moved at a given rate the throttle sleeve 28 willv be moved upwardly-at a comparatively yslow rate' at rst since the vertical component of a given arcuate movement of the arm 52 will be small when the arm is near its vertical position. As the throttle sleeve 23 approaches its open position its rate of movement relatively to the, rate of movement of the manual actuating device will of course increase materially since the lever will be approaching its horizontal position shown in Fig. l wherein the vertical Y,component of a given arcuate movement of the lever will be comparatively great.

Thus the actuating mechanisrnlprovided' tn-r ables the operator to control more accurately the fuel mixture and the resulting acceleration 'of the motor in its lower range of speeds. y justable stop device 56 on the shaft 53 outside When the manual actuating of the tubular member 49 engages an abutment on the member 49 to limit the movement of the actuating mechanism and thereby control the idling position of the throttle sleeve.

In ordery that the throttle sleeve 28 may be more easily and accurately controlled by tne operator, means is provided for counteracting the tendency of the sliding sleeve to be moved downwardly by the action of the motor suction. This means preferably includes the piston 29 and cylinder 30 which support and guide the throttle sleeve 28. A passage 57 formed in the body l2 and the wall of the cylinder` 30 extends from the passage 14 to the cylinder at a point above the piston 29. The top of the cylinder is closed by a plate 53 Thus the suction of the motor is applied directly through the passage 57 to the upper side of the piston 29 so that the same suction source which acts downwardly on the throttle sleeve 28 also acts to move the sleeve upwardly. Thus by properly proportioning the size of the piston and cylinder 30 an equalizing force is applied to the moving parts so that the operator may more easily and accurately control the movement thereof.

From the foregoing it will be apparent that the' invention provides a carburetor composed of a comparatively small number of simple parts which may be readily assembled to form a carburetor which operates 'with unusual efliciency due to the fact that the air is drawn downwardly through the carburetor and into the intake manifold so as to avoid condensation of the liquid fuel out of the fuel mixture. It will also be seen that since the principal portion of the air passes through the carburetor along a substantially straight path, the carburetor will function uniformly in all of its various adjusted positions.

It will also be apparent that since the fuel discharge ducts which are nearest to the liquid fuel l level are brought into play in the lower range of motor speeds the carburetor will provide for a more uniform motor acceleration and will also provide a more satisfactory idling fuel mixture.

I claim as my invention:

l. A carburetor comprising a body having a l`vertical passageway therethrough with a wall shaped to form the outside of a Venturi passage, means at the bottom of said passage adapted for connection with the intake manifold of a motor so that a down-draft will be produced in said pasageway, fuel supply means,.and fuel Vaporizing and mixing means within said passageway operable by air moving downwardly through said passage to produce the combustible fuel mixture and comprising a conical fuel discharge member` positioned centrally in said passage and having fuel discharge ducts, means forming an inwardly inclined annular wall on said passage' adjacent said member and an annular throttle member of wedge shaped section movable vertically intermediate said member andwall and cooperating with the wall of said conical member to form a first Venturi passage, and cooperating with the wall of said passageway to form a second Venturi passage, said annular throttle member acting to enlarge the throats of both Venturil passages simultaneously as it is moved from its idling to its open position.

2. A carburetor comprising a hollow body having a vertical passageway with its intake at the upper end and means at ,the lower end of said passageway adapted for connection with the intake manifold of a motor, so that a down-draft will be produced in said passageway, a fuel supply chamber adjacent to said passageway, a fuel discharge member supported in said passageway and shaped to form the inside of a venturi, said member having a plurality of discharge ducts therein each arranged to receive fuel from said chamber and terminating at different levels in said pasageway above the normal fuel level in said chamber, and a control member supported from above said member and movable in said passageway to control the passage of air through said passageway and past said ducts, said control member cooperating with said fuel discharge member to forma venturi with its throat substantially on a plane with the normal fuel level when the control member isin its idling position, and being movable upwardly to simultaneously raise and enlarge the throat of the venturi and draw fuel from increasing numbers of said discharge ducts.

3. Acarburetor comprising a bodyhaving asubstantially vertical passageway therethrough with a wall shaped to form the outside of a venturi and means at the lower end adapted for connection with the intake manifold of a motor so that a down-draft will be produced in said passageway, fuel discharge means shaped to form the inside of a venturi and providing a plurality of ducts opening into said passageway at different levels, and movable means for controlling the passage of fuel through said ducts cooperating with the fuel discharge means to form a rst venturi, and cooperating with the wall of said passageway to form a second venturi and operable in one position to permit passage of fuel through the lower ducts only so that only a small amount of suction will be required to draw fuel into the passageway, said movable means being operable as it is moved from said` position to shift the throat of the first venturi and draw fuel through the successively higher ducts in addition to said lower ducts.

4. A carburetor comprising a hollow body having a substantially vertical passageway therethrough, and a chamber for containing a liquid fuel, a fuel discharge member supported centrally in said passageway, said memberhaving a plurality of discharge ducts therein arranged to receive fuel from said chamber and terminating at different levels in said passageway above the normal fuel level in said chamber, control means supported from above said member and movable in said passageway to control the flow of fuel through said ducts into said passageway and including an annular member positioned between said discharge member and the wall of said passage and movable from a lower position in which it substantially closes said passage to an upper position wherein it divides said passage and directs a portion of the air past said ducts, and means at the lower end of said passageway for connecting said lower end to the intake manifold of a motor.

5. A carburetor comprising a hollow body having a substantially vertical passageway theremember having a plurality of discharge ducts therein arranged to receive fuel from said chamber and terminating at different levels in said passageway above the Inormal fuel level in said chamber, a piston in said cylinder, control means supported from said piston and movable in said passageway to control the flow of fuel through said ducts into said passageway, and means on said body for connecting said lower end to the intake manifold of a motor.

6. A carburetor comprising a hollow body having 'a substantially vertical passageway and adapted at its lower end for connection with the intake manifold of a motor so that a down-draft will lbe produced in said passageway, a float chamber adjacent to said passageway for containing liquid fuel, a fuel discharge member supported in said passageway, said member being of less diameter than said pasageway so as to permit passage of air and being of circular horizontal cross-section tapering toward its upper end, said member also having a plurality of discharge ducts therein arranged to receive fuel from said chamber and opening through the upwardly tapering surface of said member at different levels in said passageway above the normal fuel level in said chamber, and an annular control member surrounding said member and cooperating therewith to form a Venturi passage and movable up and down in said passageway to vary the position of the throat between the control member and the tapering surface of said discharge member and to control the flow of fuel through said ducts into said passageway.

7. ln a carburetor, the combination of abody having a substantially vertical passageway and adapted at its lower end for connection to an intake manifold of an engine so as to produce a down-draft through the passageway and a chamber adapted to contain liquid fuel, a fuel discharge member in said passageway having an outer surface tapering inwardly and upwardly, said member also having a fuel distributing chamber therein communicating with said oat chamber and positioned below the normal fuel level in said float chamber, a plurality of fuel discharge ducts formed in said member leading from said distributing chamber to the outside of said member at different levels on said upwardly tapering surface, and a Venturi sleeve surrounding saidy member and movable vertically along said member to vary the position of the throat vof the venturi relatively to the ends of the v'arious discharge ducts, said menber also having a passage formed therein extending from said distributingchamber to theoutside oi said member at a point lying on the compression side of the Venturi throat. l

S. In a carburetor, the combination of a body having avsubstantially vertical passageway therethrough'and a chamber adapted to contain liquid fuel, means for connecting the lowerend of said passageway to the intake manifold oi a motor soy that a down-draft will be created in said passageway, a fueldischarge member in said passageway having an outer surface tapering in-l wardly and upwardly, said member also having a fuel distributing chamber therein communicating with said float chamber and positioned below the normal fuel level in said oat chamber, and a plurality of fuel discharge ducts formed in said member leadingl from said distributing chamber tothe outside of said member at different levels on said upwardly tapering surface, and a Venturi sleeve surrounding `said member and arranged to permit passage of air downwardly therethrough, said sleeve being movable vertically along said member to vary the/position of the throat of the venturi relatively to the ends of the various discharge ducts, said member also having a passage formed therein extending upwardly from said. distributing chamber to the outside of A said member at a point lying on the compression side of the Venturi throat, said passage having a dared upper end.

9. A carburetor comprising a hollow body having a passageway therethrough, a fuel discharge member adjustably positioned in said passageway, said member having a plurality of ducts formed therein through which fuel may be drawn into said passageway, a movable control member in said passageway operable to govern the number of ducts through which fuel may simultaneously be drawnsaid control member also being operable to govern the amount of air passing through said passageway, and a third member in said passageway arranged to determine the idling position of said control member, said third member being adjustable to permit of varying said idling position and being arranged to cooperate with said control member when said control member is moved away from its'idling position to form a second air passage therebetween.

l0. A downdraft carburetor comprising, in combination, a hollow body having asubstant-ially vertical passageway therethrough and adapted at its lower end for connection to the intake manifold of a motor, a cylinder supported on said body in the upper end of said passageway, said cylinder being of less width than said passageway so yas to denne an opening between the cylinder and the wall of the passageway to percylinder, means for supplying fuel to said dis-,

charge member, a piston in said cylinder, a manually operable control member supported by said piston operable to control the ow of fuel from said discharge member and movable upwardly to increase the motor speed so that the suction in the passageway tends to move the control member downwardly to its idling position, and means providing a passage between the upper end of said cylinder and said passageway onv the suction side of said control member to substantially equalize the suction on said control member and reduce the effort necessary to raise the control member manually.

1l. A downdraft carburetor comprising,v in combination, a hollow body having a substantially vertical passageway therethrough and adapted at its lower end for connection to the intake manifold of a motor, a cylinder supported on said body in said passageway, said cylinder being of less width than said passageway so as to denne an opening between the cylinder and the wall of the passageway to permit air passing through the carburetor to traverse a substantially straight path, a piston in said cylinder, a fuel discharge member in said passageway, means ,for supplying fuel to said discharge member, a manually operable control member carried by said piston operable to control the ow of fuel from said discharge member and normally moved toward its idling position by the suction in said passage, and means providing a passage between one end of said cylinder and said passageway on the suction side of said control member substantially to ico reduce the effortnecessary to move the control member manually to increase the motor speed.

l2. A carburetor comprising a body having a vertical passageway ltherethrough with a wall shaped to form the outside of a Venturi passage, means at the bottom of said passage adapted for connection with the intake manifold of a motor so that a down-draft will be produced in said passageway, fuel supply means, and fuel Vaporizing and mixing means within said passageway operable by air moving downwardly through said passage to produce the combustible fuel mixture and comprising fuel discharge means positioned centrally in said passage and including a member shaped to form the inside of a Venturi passage, and an annular throttle member movable vertically intermediate said fuel discharge means and said wall and cooperating with the fuel discharge means to form a rst Venturi passage and cooperating with the wall of the passageway to form a second Venturi'passage, said throttle member acting to enlarge the throats of both Venturi passages simultaneously as it is moved from it idling to its open position.

13. A carburetor comprising a body having a vertical passageway therethrough with a Wall shaped to form the outside of a Venturi passage, means at the bottom of said passage adapted for connection with the intake manifold of a motor so that a down-draft will be produced in said passageway, fuel supply means, and fuel Vaporizing and mixing means within said passageway operable by air moving downwardly through said passage to produce the combustible fuel mixture and comprising fuel discharge means positioned in said passagev and shaped to form the inside of a Venturi passage, and an annular throttle member movable vertically intermediate said fuel dis, charge means and the wall of the passage and cooperating with said fuel discharge means to form a rst Venturi passage through which primary air passes to mix with the fuel from the discharge means and cooperating with the Wall of said passageway to form a second Venturi through which secondary air passes to mix with the primary air and fuel.

GUNNAR A. WAMMARK.

CERTIFICA'EE 0F CRREC'HN.

Patent No. 1,927, 426.

September i9, i933.

GUNNAR A. WAHLMARK.

.it is hereby certified that the above numbered patent was erroneously issued to the inventor said "Wahlmark" as assigner of one-third interest to "Ernest i. Svenson and Charles H. Rystrom" whereas said patent should have been issued to the inventor said "Wahimark" as assignee oi one-third interest to Ernest l. Sven' son, and one-third to Charles H. Rystrom, as individuals, as shown by the records oi assignments in this office; and that the said Letters Patent should be read with this correction therein that thesame may conform to the record of the oase in the Patent Off ice.

Signed `and sealed this 28th day of November, A. D. 1933.

(Seal) M.- Hopkins Acting Commissioner of Patents. 

